1. Field of the Invention
The present invention relates to a sensing structure of a touch panel, and more particularly, to a sensing structure of a touch panel capable of electro static discharge protection.
2. Description of the Prior Art
The touch panel has been widely used in the input interfaces of the instruments for its properties such as the diversification for design and the interaction between machines and humans. In recent years, more consumer electronics, such as mobile phones, GPS navigator systems, tablet computers and laptop computers, are employed with touch display panels.
There are many diverse technologies of touch panel, and the resistance touch technology, the capacitive touch technology and the optical touch technology are the main touch technologies. The capacitive touch technology has become the mainstream touch technology for the high-end and the mid-end consumer electronics, because the capacitive touch panel has advantages such as high precision, multi-touch, better endurance, and higher touch resolution.
A capacitive touch panel is disclosed in T.W. Pat. No. M375,934 issued Mar. 11, 2010 to Wu. The capacitive touch panel includes a plurality of first electrode sets and a plurality of second electrode sets disposed vertically. Each of the first electrode sets includes a plurality of first transparent electrodes and a plurality of conducting lines electrically connected with the two adjacent first transparent electrodes. Each of the second electrodes sets includes a plurality of second transparent electrodes, and a connecting point is disposed between a conducting line and the two adjacent second transparent electrodes. The connecting point includes a transparent insulating layer covering each of the conducting lines, an ESD protection line connected to the two adjacent second transparent electrodes over the transparent insulating layer, and a metal line disposed on the surface of the ESD protection line, wherein the two ends of the metal line are disconnected with the two adjacent second transparent electrodes. Because the electrical signals of the second electrode set are transmitted via the ESD protection lines and the metal lines, the ESD protection effect of the metal lines is enhanced.
Please refer to FIG. 1. FIG. 1 is a schematic diagram illustrating a top view of the conventional sensing structure of the touch panel. As shown in FIG. 1, the conventional sensing structure of the touch panel includes a plurality of first sensing electrodes 14C, a plurality of second sensing electrodes 14D, and a plurality of bridges 11. The first sensing electrodes 14C are disposed interlacedly with the second sensing electrodes 14D. Each of the second sensing electrodes 14D is electrically connected with the adjacent second sensing electrodes 14D in a horizontal direction X. In a vertical direction Y, each of the first sensing electrodes 14C is electrically connected with the adjacent first sensing electrodes 14D via the bridge 11. The bridges 11 and the first sensing electrodes 14C/second sensing electrodes 14D are disposed on different layers. In the capacitive touch technology, the sensing electrodes are used to detect the variations of electrical capacitances around the touch points, and the feedback signals are transmitted via the connecting lines along the direction X and the direction Y for positioning the touch points. When operating the capacitive touch panel, electro static charges may be generated and result in an electro static discharge (ESD) phenomenon in the touch panel. Because the resistance inside the touch panel is close to zero, a heavy current may be generated by the ESD in the touch panel. The heavy current may pass through the bridges 11, which have relatively higher resistance. An electric energy may be released at the bridge 11 and burn down the bridges 11. The reliability of the touch panel is affected seriously by the ESD damages, and therefore, a solution for ESD damages is eagerly demanded.